The Megaton armory is the town's most heavily secured location. The armory is Megaton's primary weapons and ammunition depot. It also houses the computer terminal used to control both Deputy Weld, and Deputy Steel.
It has a very hard lock on the door. As you enter, Deputy Steel is in front, ready to protect the arsenal from thieves, including you. On the right is a counter with two hunting rifles, a combat shotgun, 1-2 10mm pistol and three Chinese assault rifles on it. Next to it is a metal shelf with a metal box on it. In the back there is a cabinet and beside that is a hard locked terminal that allows you to deactivate Deputy Steel and Weld, and along the left wall is a ruined couch.
Sheriff Lucas Simms' key will open the armory. If anybody sees you entering the Armory, the whole town's population will turn hostile. A safe way to obtain the key is to allow Simms to die during the quest The Power of the Atom, then loot his body. Another way is to pickpocket the key from Sheriff Simms before you enter the armory, you can then use a Stealth Boy and sneak allowing you to loot the armory in front of the unaware Deputy Steel.
Sometimes, entering the armory undetected will cause the whole town turn hostile.
Hacking the terminal requires a Science skill of 75 to disable Deputy Steel and is a temporary solution, as he will be operational a few days later.
Xbox 360 If you initiate combat with Deputy Weld (the protectron outside of Megaton), Deputy Steel along with Lucas Simms will come to back him up, which may remove Deputy Steel from the armory. In the newer versions of the game (i.e. Game of the Year Edition) this option is not possible, Deputy Steel keeps his place in the armory and no one moves into Deputy Weld's position outside Megaton.